PROTOCOL: In‐person interventions to reduce social isolation and loneliness: An evidence and gap map

Abstract This is the protocol for an evidence and gap map. The objectives are as follows: This EGM aims to map available evidence on the effects of in‐person interventions to reduce social isolation and/or loneliness across all age groups in all settings.

Social isolation is the objective lack or paucity of social contact and infrequent interactions with others (Badcock et al., 2022;Donovan et al., 2020;Leigh-Hunt et al., 2017). Loneliness is a related concept defined as the subjective, negative feeling of inadequate meaningful connections resulting from an unmet need or discrepancy between desired and actual social relationships Prohaska et al., 2020). Loneliness has two components: an emotional component (unpleasant, negative feeling) and a social cognition component (perception of social disconnection from other people with a desire to be connected) (Badcock et al., 2022). Loneliness can also be a transient normal experience or chronic with negative physical and mental health consequences Qualter et al., 2015).
The two concepts, social isolation, and loneliness, are distinct; social isolation is objective and associated with social contact while loneliness is subjective and related to social connectedness (O'Rourke et al., 2018). One may occur without the other, although they are related and may also co-occur. When social isolation and loneliness co-occur, the risk of mortality is exacerbated (Beller & Wagner, 2018).
People may have a social network and feel lonely, while some with a small network may not.
Social isolation and loneliness can occur across all age groups and are associated with serious health consequences including anxiety and depression, cardiovascular disease, and premature mortality (Cené et al., 2022;Leigh-Hunt et al., 2017). Poor relationships are associated with 32% increased risk of stroke, 29% increased risk of coronary heart disease (Cené et al., 2022;Valtorta et al., 2016), and 26% increased risk of all-cause mortality (Donovan et al., 2020;Holt-Lunstad et al., 2015). Incident depression and dementia have a bi-directional relationship with both social isolation and loneliness (Cené et al., 2022;Donovan et al., 2020) although several studies have reported that dementia is associated with loneliness than social isolation (Cené et al., 2022;Holwerda et al., 2014;Rafnsson et al., 2020). Both social isolation and loneliness are associated with negative health-related behaviors such as smoking and physical inactivity (Cené et al., 2022;Menec et al., 2020). The negative health impacts of social isolation and loneliness have been shown to increase health and social care service use (Cotterell et al., 2018;Windle et al., 2012). These negative impacts occur when contextual and risk factors affecting social relationships persist and individuals do not use appropriate coping strategies to address them (Akhter-Khan et al., 2022;Elder et al., 2012).
Since the onset of the COVID-19 pandemic, movement restriction policies have made social isolation and loneliness prominent global issues and a public health priority (Galvez-Hernandez et al., 2022;WHO, 2021). The prevalence of severe loneliness increased by 15% and social isolation by 13% in adults 18 years or older across 101 countries during the pandemic . Small increases in the prevalence of loneliness were also observed in a recent synthesis of longitudinal studies during the COVID-19 pandemic (Ernst et al., 2022). The prevalence is hard to measure across the lifespan because of the lack of standardized measurement instruments and definitions, and the use of different cut-off points and age categories Prohaska et al., 2020). A recent systematic review and meta-analysis on the prevalence of loneliness pre-COVID-19 pandemic across 113 countries (Surkalim et al., 2022) showed varying rates for adolescents (9.2%-14.4%), young adults (1.8%-9.4%), middle-aged adults (2.4%-12%), and older adults (4.2%-24.2%) depending on the country. A prevalence study in a population-based adult cohort showed that social isolation increases with age from 5.4% (95% confidence interval [CI]: 4.7 to 6.0) in the youngest age group (18-39 years) to 21.7% (95% CI: 19.5 to 24.0) in the oldest age group (70-79 years) . The global prevalence of social isolation in communitydwelling older adults was found to be 25% (95% CI: 21 to 30) (Teo et al., 2022). Most of the studies were conducted in high income countries, especially in Europe, with very few in low-middle-income countries (Fakoya et al., 2020;Surkalim et al., 2022).
Both social isolation and loneliness are linked to less social support and can be triggered by situational factors such as adversity, significant life changes or transitions, such as moving away from home, starting a new job, becoming a new parent, illness, and the death of a spouse or parent (Badcock et al., 2022;Elder et al., 2012;Lim et al., 2020;Qualter et al., 2022). They are associated with risk factors including individual factors (e.g., personality, maladaptive cognition, poor health, disability or mobility impairment, cognitive impairment), interpersonal or social factors (e.g., peer victimization or discrimination, poor relationship quality, quantity of friends or social contacts, living alone), socio-environmental factors (e.g., neighborhood deprivation, inaccessible location of residence, housing, cultural prejudice), and demographic factors (e.g., age, gender, educational level, low socio-economic status, unemployment) (Badcock et al., 2022;Elder et al., 2012;Lim et al., 2020;O'Sullivan et al., 2021;Qualter et al., 2022).
Many systematic reviews have evaluated the effectiveness of interventions to reduce social isolation or loneliness with conflicting findings demonstrating a need for better quality research Victor et al., 2018;Williams et al., 2021). A number have focused on older adults, but social isolation and loneliness affect people across the life span, including young people Surkalim et al., 2022), with interventions designed specifically for them (Eccles et al., 2021). Most of the reviews have focused on people living in the community or long-term care settings (Fakoya et al., 2020;Grenade et al., 2008). There is limited research addressing social isolation and/or loneliness for patients in clinical settings (NASEM, 2020). Studies that consider hospitalized patients focus on screening and detection of loneliness and social isolation, the impact of social isolation and loneliness on health service use and which interventions may be used rather than the assessment of the effectiveness of interventions to reduce social isolation and loneliness (Grenade et al., 2008;NASEM, 2020;Proffitt et al., 1993;Razai et al., 2020;Zamir et al., 2018).
The impact of interventions has been found to differ depending on population characteristics such as coping skills, needs, degree of loneliness, and contextual factors like age, socioeconomic status, health condition, and place of residence (Fakoya et al., 2020).
Therefore, there is no one-size-fits-all approach, and it is important to tailor appropriate interventions to individuals' needs and contexts Fakoya et al., 2020;Mann et al., 2017).
There are health equity issues related to social isolation and/or loneliness such as the gap in evidence from low-middle income countries (Surkalim et al., 2022), limited access to interventions caused by disabilities and lack of transportation, or limited programs in rural areas compared to urban areas (Dassieu et al., 2021;NASEM, 2020;Qualter et al., 2022). Social isolation and/or loneliness related to structural inequities (e.g., intersectional discrimination across race, gender, socioeconomic status; age-based discrimination and ethnic minorities), have a negative impact on health outcomes (Dassieu et al., 2021).
This current evidence and gap map will identify areas where evidence is available, as well as any gaps in research related to in-person interventions for social isolation and loneliness across any age.
Several approaches have been used to categorize interventions in some reviews. The interventions have been categorized by the format or delivery mode or type as one-on-one or group-based (Cohen-Mansfield et al., 2015;Dickens et al., 2011;Fakoya et al., 2020;Findlay, 2003;Hagan et al., 2014;Masi et al., 2011;Poscia et al., 2018), or technology or non-technology (in-person) based (Eccles et al., 2021;Masi et al., 2011). They have also been categorized by the type, or strategy, being classified as interventions for social skills training, enhancing social support, enhancing social interaction or social cognition training . Other terms have been used as a rationale for categorization, such as the focus, This evidence and gap map will focus on in-person interventions that are non-technology based and delivered face-to-face since there is a gap map on digital interventions for older adults (Welch et al., 2022b).

| Why it is important to develop the EGM
The existing body of evidence for interventions to mitigate social isolation and/or loneliness is characterized by small, low-quality trials, with inconsistent terminology and conclusions on their effectiveness (Eccles et al., 2021;Fakoya et al., 2020;Prohaska et al., 2020;Veronese et al., 2021). With the rapid growth of evidence in this sector, this evidence and gap map will demonstrate areas where evidence is available and areas where there are gaps that researchers, decision and policymakers could use to help select interventions and prioritize future research. It will also improve the discoverability of evidence on different types of interventions and enhance their use for informed decision-making by stakeholders including health and social care providers, policymakers, citizens, caregivers, and patients. low-quality reviews and few studies on older people who are not caregivers or who do not have a particular chronic illness. Our group is currently working on another gap map on digital interventions for older adults with a broader scope of interventions and including caregivers Welch et al., 2022b), but there is currently no mapping of evidence for in-person interventions to reduce social isolation and loneliness across all ages.

| OBJECTIVES
This EGM aims to map available evidence on the effects of in-person interventions to reduce social isolation and/or loneliness across all age groups in all settings.
Specific objectives are as follows: 1. To identify existing evidence from primary studies and systematic reviews on the effects of in-person interventions that are nontechnology based and delivered face-to-face to reduce social isolation and/or loneliness across all age groups.
2. To identify research evidence gaps for new high-quality primary studies and systematic reviews.

To highlight evidence of health equity considerations from
included primary studies and systematic reviews.

| METHODS
We will follow the Campbell Collaboration guidance for producing an evidence and gap map .

| Evidence and gap map: Definition and purpose
Evidence and gap maps are a systematic evidence synthesis product with a visual presentation of existing evidence relevant to a specific research question (Snilstveit et al., 2013;White et al., 2020). They display areas where evidence is available, areas where there are gaps in evidence, and the quality of existing evidence.
The evidence and gap map is typically a two-dimensional matrix with interventions as row headings and outcomes as column headings (Snilstveit, 2016;White et al., 2020). The studies with evidence on the corresponding intervention and outcome are shown within each cell of the matrix. This map will identify areas of evidence and any gaps in research related to using in-person interventions for social isolation and/or loneliness across all ages.

| Framework development and scope
We developed an intervention-outcome framework by adapting our conceptual framework from the digital interventions EGM . We expanded the non-digital intervention and outcome categories to attain evidence-based, clear and distinct categories that are practical and useful to a broad audience by using several existing frameworks, reports, and reviews.
In consultation with stakeholders, we identified and reviewed other frameworks including the framework described by Masi (Masi et al., 2011), the framework for the Campaign to End Loneliness by Jopling (Jopling, 2020), the framework by Mann , and the socio-ecological framework adapted by the World Health Organization for strategies to reduce social isolation and loneliness (WHO, 2021), the framework for evidence-based interventions for youth reporting loneliness (Qualter et al., 2022) Social isolation and loneliness are associated with the lack of meaningful social connections which can occur at any of these four levels (Holt-Lunstad, 2018Lim et al., 2020;Ogrin et al., 2021). Risk factors for social isolation and loneliness can be co-occurrent, inter-related, and can operate at multiple levels Lim et al., 2020;Qualter et al., 2022). Interventions may target risk factors at multiple levels of the socio-ecological model by creating and maintaining meaningful social connections or a combination of other mechanisms, such as changing negative social cognition or providing support to enhance social interactions.
We will consider non-technology-based interventions delivered in-person to alleviate social isolation and/or loneliness across all age groups in all settings. None of the existing frameworks or taxonomies provide mutually exclusive categories and subcategories for classifying the interventions for this evidence and gap map. They all demonstrate the complexity, diversity, and interdependencies of contextual or risk factors, and mechanisms that shape social relationships.
We will therefore focus on delivery and classify interventions into five main categories based on who is providing the intervention and where it is provided: self delivery, interpersonal delivery, communitybased delivery, societal level delivery, and multi-component or complex interventions.
Outcomes will be based on the level of impact of interventions. The impact of social isolation and loneliness interventions depend on how well they were implemented, therefore, we will consider both process indicators or implementation outcomes and other outcomes including health and psychosocial outcomes, indicators of social connections as well as cost and cost-effectiveness outcomes (Jopling, 2020;Windle et al., 2012).

| Stakeholder engagement
We established an Advisory Board of key stakeholders to contribute toward defining the scope and developing the framework for the map as well as interpreting the findings. They include academics, advocates, policy and decision-makers, from relevant organizations (e.g., WHO, Canadian Red Cross, Global Initiative on Loneliness and Connection, US Foundation for Social Connection, and Ending Loneliness Together) who are involved in research and working to address social isolation and loneliness.
The Advisory Group met virtually on December 13 and 16, 2021 to discuss the scope of the evidence and gap map and existing frameworks that could be considered in developing the intervention-outcome framework for this evidence gap map. They met again in June 2022 to provide feedback on the framework.
They will be consulted to provide feedback on the revised framework and on the preliminary findings and draft map.

| Conceptual framework
The conceptual framework (Figure 1) considers possible pathways for interventions to bring about expected changes and outcomes based on the understanding of the population risk factors and needs that may trigger social isolation or loneliness. It is based on theoretical underpinnings with the following key components: • population contexts, risk factors and needs that may trigger social isolation or loneliness.
• types of interventions required to address social isolation or loneliness, • the mechanisms of change by which the interventions address social isolation or loneliness, and • process indicators (e.g., acceptability) and outcomes (e.g., loneliness).

| Population targeted by interventions
Social isolation and loneliness are complex public health issues and their occurrence across the lifespan is influenced by individual | 5 of 18 contextual and risk factors, needs, expectations, and coping skills which are all inter-related and influence relationship ties (Akhter-Khan et al., 2022;Elder et al., 2012;Gardiner et al., 2018;O'Rourke et al., 2018;Qualter et al., 2022). Contextual and risk factors such as structural changes that may cause displacement (e.g., moving schools or wars), living situations (e.g., living alone or in a care facility such as orphanage, long-term care home), resources (available activities or social supports) affect people's motives, expectations, coping skills, and social relationships. Coping skills and social supports may be a protective factor if they allow people to promote their wellbeing or resilience. On the other hand, inadequate coping skills and social supports may be a risk factor for social isolation or loneliness.
Based on a public health approach, interventions may target anyone regardless of risk (universal), or target subpopulations at high risk (selective) or socially isolated or lonely people (indicated) . Categorizing target populations into these three orders gives a clearer picture and understanding of whom to prioritize and how to allocate resources more efficiently.

| Risk factors
Social isolation or loneliness may be triggered in both young and old across the life span by situational factors such as significant life events or transitions (e.g., adversity, moving away from home, retirement, death of a spouse, friend or relative) and may be associated with risk factors including physical and mental health factors (e.g., poor health, maladaptive cognition or cognitive decline, disability or impaired mobility, personality), interpersonal or social factors (e.g., living alone, peer victimization, social contacts, relationship quality,), socio-cultural or environmental factors (e.g., neighborhood deprivation, inaccessible location of residence, cultural individualism, social discrimination, and stigma) and demographic factors (e.g., age, gender, socio-economic status) (Dahlberg et al., 2022;Elder et al., 2012;Lim et al., 2020;NASEM, 2020;Qualter et al., 2022). Social support is a major component of social connection and may be provided to meet different needs. Social support can take the forms of instrumental/tangible, informational, emotional or belonging support (Elder et al., 2012;NASEM, 2020). It can be perceived, or actual support provided through social connections with other people and through different sectors including health, transportation, housing, work, nutrition, environment, education, leisure: arts and entertainment .

| Needs assessment
Loneliness is also associated with social relationship expectations that are influenced by personal, social, cultural and historical contexts and include the availability of social contacts (proximity), feeling cared for and relying on others (support), feeling close, understood, and listened to (intimacy), sharing interests and enjoyable experiences (fun), having opportunities to contribute meaningfully (generativity) and feeling valued and actively included (respect) (Akhter-Khan et al., 2022). A discrepancy between expected and actual social relationships will result in loneliness.

| Interventions
Interventions to reduce social isolation and/or loneliness are more  Masi et al., 2011;Ogrin et al., 2021). Some interventions involve building skills, purposeful activity, or implementing a philosophy of care within a facility (Akhter-Khan et al., 2022). Some interventions are complex and may address social isolation or loneliness through multiple or poorly specified mechanisms (Akhter-Khan et al., 2022;Holt-Lunstad, 2018;Lim et al., 2020).

| Process indicators and outcomes
The potential of interventions to reduce social isolation or loneliness have been assessed through their acceptability, adherence, and feasibility. These process indicators determine progress toward outcomes such as health and psychosocial outcomes (e.g., loneliness, social isolation, social connectedness), indicators of social connections (e.g., social support, social engagement, social cohesion), as well as cost and cost-effectiveness outcomes. See Glossary of terms (Supporting Information: Appendix 1).
We will use this conceptual framework to define and code the intervention and outcome categories and subcategories for the two-dimensional matrix in the evidence and gap map.

| Types of study design
We will include on-going and completed systematic reviews and primary studies with any study design that has a control group: randomized controlled trials, non-randomized studies including control before-after, and statistical matching quasi-experimental studies.
The inclusion of systematic reviews will be based on the population, intervention, comparison, outcome (PICO) framework and if they meet at least four of the five criteria of a systematic review as defined by Moher et al. (Moher et al., 2015). That is, they describe adequate search methods used to identify studies, eligibility criteria for selection of studies, methods of critical appraisal of included studies, sufficient details or characteristics of included studies, and synthesis or analysis of findings of the included studies.
Eligible quasi-experimental designs include quasi-randomized studies, regression discontinuity designs, natural experiments, non-equivalent comparison group designs and interrupted series designs with at least three data points before and after a discrete intervention .
We will exclude any study designs with no control group such as longitudinal cohort studies and cross-sectional studies, and those studies with interrupted time series designs with less than six data points.
We will include mixed methods studies, but exclusive qualitative research will be excluded.
We will include studies irrespective of their publication status. WELCH ET AL. | 7 of 18 3.5.2 | Types of intervention/problem We will include any intervention which aims to reduce social isolation and/or loneliness that is delivered in-person regardless of the intensity, duration, and frequency of administration. We will exclude digital or technology-based interventions.
Included interventions may be one-on-one or group based and will be categorized based on our conceptual framework as self-guided delivery, interpersonal delivery, community-based delivery, societal level delivery as well as multi-component or complex interventions. See Table 1 for subcategories and examples.
Comparison interventions will include no interventions, other interventions, or usual care.
If reviews include a subset of interventions that is not eligible, we will only code studies with the eligible interventions.

| Types of population (as applicable)
We will consider any age group, people with or at risk of social isolation or loneliness, or the general population, whether based on case finding or screening for vulnerability or not.

| Types of outcome measures (as applicable)
We will consider the following types of outcomes: • health and psychosocial outcomes, • indicators of social connections, • cost and cost-effectiveness outcomes, and • process indicators (or implementation outcomes).
We will consider adverse effects of interventions such as psychological distress, safety and others as described by the studies. Different measuring tools have been used for loneliness, social isolation, and related outcomes. See Table 2 for outcome categories and measurements.
We will not use outcomes as eligibility criteria; however, eligible studies and reviews must assess interventions with a primary objective to reduce social isolation and/or loneliness. Studies and reviews assessing interventions with a stated aim to reduce social isolation and loneliness will be included. Those that assess the effects of interventions on social isolation and/or loneliness as a primary outcome or considered other indicators of social connections, such as social support, social engagement, social cohesion, and social capital will also be included.
Studies and reviews assessing the effect of interventions on indicators of psychological wellbeing such as quality of life, anxiety or depression, with a focus on mental health rather than social isolation or loneliness will be excluded.

| Other eligibility criteria
Types of location/situation (as applicable) We will include all countries. We will also classify the countries by the We will not exclude primary studies and systematic reviews that do not report the countries.

Types of settings (as applicable)
We will include all settings, for example, residential or personal home, nursing home or long-term care, assisted living facilities, orphanages, schools, workplaces, community centers, and medical facilities. The reference lists of all included systematic reviews will be screened in Eppi-Reviewer to identify additional studies.

| Report structure
We will follow the reporting structure of Campbell EGMs with the standard headings: abstract, plain language summary, background, methods, results, discussion, and conclusion.
The report will include the description of the study flow with included studies, excluded studies, and any studies awaiting T A B L E 1 Types of interventions.

Intervention categories Subcategories Examples
Self-delivery Self-guided changing cognition -Self-guided mindfulness therapy -Self-guided reminiscence therapy Self-guided social skills training and psychoeducation -Solitary social skills training -Psychoeducation, e.g., gratitude Interpersonal delivery Changing cognition led by a health professional -Cognitive behavioral therapy -Mindfulness therapy -Reminiscence therapy Social skills training and psychoeducation led by a health professional -Friendship enrichment program -Family therapy -Psychosocial school intervention Healthcare support -Hearing aids -Social prescribing (Primary care referral to support services) Social support -Community navigators

Community-based delivery
Group activities -Activities aimed at bringing people together through shared interests as well as facilitating social connection, e.g., education or health promotional activities (gardening, exercise, or fitness program) Support groups -Group-based interventions for people with common conditions or risk factors for social isolation or loneliness, e.g., diabetes, bereavement, caregivers | 9 of 18 assessment as well as the PRISMA study flow diagram. We will also present the conceptual framework and tables and figures summarizing the distribution of included primary studies and systematic reviews across all the coding categories such as study designs, publication status, quality of systematic reviews, types of interventions, types of outcomes, population characteristics, settings, geographic distribution.
The evidence and gap map will have interventions as the row dimension and outcomes as the column dimension. We will use bubbles of different sizes to represent included primary studies and systematic reviews and different colors to distinguish primary studies and methodological quality of systematic reviews. The number of included studies and coded information will determine which filters will be used in the map. See a sample of the map in Figure 2.

| Filters for presentation
Additional dimensions of interest used as filters will include:

| Equity analysis
We will assess equity following the same methods used in the evidence and gap map on digital interventions to reduce social isolation and loneliness in older adults

| Dependency
We will treat multiple reports of the same study as one study. A study with multiple outcomes and interventions will be shown multiple times on the map (once for each outcome or intervention identified).
Primary studies will be mapped regardless of whether they are included in multiple systematic reviews. Systematic reviews will be F I G U R E 2 Sample map.
WELCH ET AL.
| 11 of 18 mapped to interventions and outcomes based on their PICO question.

| Screening and study selection
Pairs of reviewers will use Machine learning text mining in Eppi-Reviewer web-based software program  to screen titles and abstracts independently (EG, SD, EB, VB, TH, AW, AA, PD, JH, RD, SA, RI, LM, AAA, AJ, and FJ). We will initially screen 10% of the titles and abstracts. The priority screening function will develop a classifier based on the probability of inclusion determined from the preliminary screening results and present the most likely studies to be included first. We will manually screen all the articles to ensure all potentially eligible studies are captured for the full text screening stage which will also be conducted by two reviewers independently.
We will also screen the reference lists of included systematic reviews to identify additional studies that may have been missed in the database searches.
All screening will be done following the eligibility criteria (see Supporting Information: Appendix 3).

| Data extraction and management
We will develop and pilot test a data extraction code set in Eppi-Reviewer for data collection (see draft in Supporting Information: Appendix 4). We will use a set of included studies for testing. The same studies will be coded by all the reviewers and the coding will be assessed for agreement. Any discrepancies will be discussed, and description of the coding criteria will be modified for clarity as necessary. After the pilot test, members of the team (EG, SD, EB, VB, TH, AW, AA, PD, JH, RD, SA, RI, LM, AAA, AJ, and FJ) will individually extract and code data. Non-English papers will be coded by CWY, RY and TAMTM. Automation and text mining will not be used for coding.
We will code the study characteristics (study design, publication status, methodological quality assessment of systematic reviews), categories and subcategories of interventions and other intervention characteristics (focus, sectors, goals, and risk factors targeted), outcome domains and subdomains, population characteristics (using PROGRESS-Plus acronym), settings, locations (by country, WHO region, and World Bank income classification).
We will code how populations were recruited and whether they were selected based on disadvantages across any PROGRESS-Plus factors.
We will also code whether differential analysis across any PROGRESS-Plus factors was conducted in the studies and systematic reviews to understand any equity issues.
We will not contact authors of studies or systematic reviews for any missing information given the expected size of the map (over 300 studies).

| Tools for assessing risk of bias/study quality of included reviews
Pairs of reviewers will use the AMSTAR 2 tool  to assess the quality of systematic reviews independently. Any disagreements will be resolved by discussion. Primary studies will not be assessed for risk of bias or methodological quality following guidance for evidence maps (Snilstveit, 2016;White et al., 2020).

| Methods for mapping
We will use the EPPI-Mapping tool (Digital Solution Foundry and EPPI_Centre, 2020) to develop the evidence and gap map.

ACKNOWLEDGMENTS
We acknowledge the contribution of Tarannum

CONTRIBUTIONS OF AUTHORS
The recommended optimal EGM team composition includes at least one person who has content expertise, at least one person who has methodological expertise and at least one person who has statistical expertise. It is also recommended to have one person with information retrieval expertise. Dr. Kate Mulligan has been a contract consultant for the Canadian Red Cross, a provider of in-person interventions to reduce social isolation and loneliness. She has also been involved in intervention projects related to social prescribing with the Alliance for Healthier Communities.